1. Field of the Invention
This invention relates in general to DC motor starting circuits and more particularly to DC motor starting circuits that are testable on-line.
2. Background of the Invention
One of the new generation advanced passive nuclear power plants supplied by Westinghouse Electric Company, LLC, Pittsburgh, Pa. known as the AP1000 plant, has no class 1E AC power source. The plan is to use the 125 VDC power station batteries to operate safety grade valves to control various aspects of the nuclear power generation process. The intent is to use DC motors to operate valves that are either to large for solenoid powered operators or which must have a “fail-as-is” characteristic. A suitable DC motor starter is not commercially available to meet the particular requirements of nuclear class 1E equipment.
Additionally, the trend has been to increase the operating fuel cycles of nuclear plants to enhance their efficiency. This mode of operation puts a further strain the reliability of the nuclear components due to the extended time between outages during which the equipment may be serviced.
Accordingly, it is an object of this invention to provide a solid state reversing DC motor starter that can meet the stringent requirements of nuclear safety systems.
Furthermore, it is an object of this invention to provide such a solid state reversing DC motor starter that is testable on-line to ensure its integrity.
Further, it is an object of this invention to provide such a DC motor starter that is immune to single failure caused spurious actuations.
It is also an object of this invention to provide such a DC motor starter that is testable on-line without requiring motion of the motor.